Pleso means lake. There is a plesant path around the lake. Towards the mountains you will see the ski jumping places. If you walk a bit more towards the mountains from the back of the lake you will reach a chair lift which takes you up part of a mountain.
More or less opposite the railway station there is a tourist information office.
While being on the High Tatras in Slovakia, one must not forget his camera with him/her cause its an amazing place for taking photographs! i couldnt stop! besides that, a good sports shoes is recommended to walk over there!